This program addresses the identification of antigens of leishmania which can induce and elicit T cell responses, including proliferation and cytokine production, and which can be used with specificity and sensitivity in serological tests. For evaluation of T cell responses, we will focus primarily on leishmania specific human T cell lines and clones. The phenotype of T cells responding to particular antigens will be emphasized. Candidate antigens will be cloned in E. coli. We will use conventional approaches as well as a novel approach for identifying cloned genes. The novel approach consists of screening transfected antigen presenting cells with leishmania-specific T cell lines, followed by isolation of the cloned cDNA of interest. For expression of antigen genes, we will emphasize yeast and mammalian cell systems. Cellular and molecular aspects of T cell responses are measured following stimulation with purified or recombinant proteins which we have produced. Peptide fragments of promising antigens will be similarly tested. Antigens which are effective in these assays will be tested in mice, in particular for their ability to protect against acute disease and to induce T cells capable of transferring similar protection to syngenic recipients. Finally, antigens will be evaluated as sero-diagnostics, using new methods which we have developed.